The dream of an effective vaccine against the AIDS virus may have moved one step closer to reality, according to federal scientists.

The scientists identified 2 naturally occurring antibodies that destroy nearly 90% of all strains of HIV, the virus that causes AIDS. They say their finding could hasten development of new HIV treatments as well as a vaccine.

HIV is deviously mutable. Frequent mutations in its DNA change the composition of surface proteins on the virus, allowing it to escape an immune response. This enables the virus to continue infecting cells even after antibodies targeting it have appeared — it has thus been able to avoid vaccines developed against it so far.

There are hundreds of variants of the HIV virus around the world. Finding so-called broadly neutralizing antibodies that can kill the majority of these strains has been the goal of HIV researchers for 2 decades.

To date, the best researchers have been able to do is find antibodies that block about 40% of the known HIV strains. Key to a breakthrough in this regard is to isolate antibodies that attack relatively unchanging parts on the surface of the HIV virus. And that’s what may just have been accomplished.

“I am more optimistic about an AIDS vaccine at this point in time than I have been probably in the last 10 years,” Gary Nabel of the National Institute of Allergy and Infectious Diseases told the LA Times. Nabel headed the project reporting the breakthrough. The write-up appears in Science.

Nabel’s team isolated antibodies from a 60-year-old African American man that had been infected with HIV. Using new imaging and analytical techniques, the team isolated 2 antibodies, known as VRC01 and VRC02, which are directed against a protuberance on the surface of the HIV virus. The spike facilitates binding to something called the CD4 binding site on white blood cells of humans. When an antibody binds to to the spike, it prevents the virus from entering the cell.

The HIV virus relies exclusively on this receptor to enter human white blood cells, so it can’t infect them when antibodies are attached to the spike.

Nabel’s team is currently testing a synthetic version of the spike as a possible vaccine in animals. They hope to begin human testing fairly soon.